Well the gravitational 'range' of an object is not infinite. The roce of the expansion of the universe so far is greater than the force of it's condensation, thus suggesting that the Big Rip or Big Freeze are the most likely ending scenarios of the Universe. You see, you can have a constantly expanding bubble filled with gases, and eventually the gases will start condensing into smaller, condensed pockets, whilst the force of expansion will the drive the galaxies farther and farther away from each other.
IE: Imagine you have a bunch of small magnetic marbles, and a curved, circular floor that is covered in metallic dust. Droop the magnetic balls on the floor, and as they go outwards from the center, they'll pick up tons of the metallic dust, whilst the balls themselves get farther and farther apart from each other. However, this isn't the whole story, as some of the odd movements of the universe and its galaxies suggest that the vast empty parts of space aren't so empty, but rather possibly filled with dark matter...
Edit: Then again, I do not yet comprehend the mathetmics involved behind a lot of the advanced physics theories, so I may have explained this incorrectly.
Edit: Sorry for the bad spelling of this post. My fingers are really cold because my home's heater isn't working.
Please feed the trolls. XD